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Date:   Fri, 29 Jul 2022 16:26:34 +0200
From:   Oleksij Rempel <o.rempel@pengutronix.de>
To:     Fedor Pchelkin <pchelkin@ispras.ru>
Cc:     Robin van der Gracht <robin@protonic.nl>,
        Oleksij Rempel <linux@rempel-privat.de>, kernel@pengutronix.de,
        Oliver Hartkopp <socketcan@hartkopp.net>,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, linux-can@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Alexey Khoroshilov <khoroshilov@ispras.ru>,
        ldv-project@linuxtesting.org
Subject: Re: [PATCH v2] can: j1939: Replace WARN_ON_ONCE with
 netdev_warn_once() in j1939_sk_queue_activate_next_locked()
Message-ID: <20220729142634.GD10850@pengutronix.de>
References: <20220728165828.GB30201@pengutronix.de>
 <20220729140609.980154-1-pchelkin@ispras.ru>
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On Fri, Jul 29, 2022 at 05:06:09PM +0300, Fedor Pchelkin wrote:
> We should warn user-space that it is doing something wrong when trying to
> activate sessions with identical parameters but WARN_ON_ONCE macro can not
> be used here as it serves a different purpose.
> 
> So it would be good to replace it with netdev_warn_once() message.
> 
> Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
> 
> Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
> Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>

Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>

> ---
> v1 -> v2: Used netdev_warn_once() instead of pr_warn_once()
> 
>  net/can/j1939/socket.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
> index f5ecfdcf57b2..09e1d78bd22c 100644
> --- a/net/can/j1939/socket.c
> +++ b/net/can/j1939/socket.c
> @@ -178,7 +178,10 @@ static void j1939_sk_queue_activate_next_locked(struct j1939_session *session)
>  	if (!first)
>  		return;
>  
> -	if (WARN_ON_ONCE(j1939_session_activate(first))) {
> +	if (j1939_session_activate(first)) {
> +		netdev_warn_once(first->priv->ndev,
> +						 "%s: 0x%p: Identical session is already activated.\n",
> +						 __func__, first);
>  		first->err = -EBUSY;
>  		goto activate_next;
>  	} else {
> -- 
> 2.25.1
> 
> 

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